Bulk acoustic wave filter

Abstract

The invention describes a filter arrangement as well as an electronic component, each with a bulk acoustic wave resonator unit which is present on a carrier substrate ( 1 ). A reflection element ( 2 ) is provided between the carrier substrate ( 1 ) and the bulk acoustic wave resonator unit for the purpose of acoustic insulation of the generated oscillations. This reflection element ( 2 ) may consist either of several layers of alternately high and low impedance or, if the acoustically reflecting substance has a sufficiently low impedance, of a single layer. In addition, a mobile telephone device, a transmitter, a receiver, and a wireless data transmission system as well as a method of manufacturing an electronic component are described.

What is claimed is:  
     
       1. A filter arrangement with a carrier substrate ( 1 ), a resonator unit, and a reflection element ( 2 ) between the carrier substrate and the resonator unit, characterized in that the reflection element ( 2 ) consists of a unitary layer formed of an acoustically reflecting substance selected from the group consisting of silica aerogel or organic aerogel, xerogel, glass foam, foam-type adhesive, foamed synthetic resin and a low density synthetic resin. 
     
     
       2. A mobile telephone device provided with a filtier arrangement having a carrier substrate ( 1 ), a resonator unit, and a reflection element ( 2 ) between the carrier substrate ( 1 ) and the resonator unit, characterized in that the reflection element ( 2 ) consists of a unitary layer formed of an acoustically reflecting substance selected from the group consisting of silica aerogel or organic aerogel, xerogel, glass foam, foam-type adhesive, foamed synthetic resin and a low density synthetic resin. 
     
     
       3. A transmitter provided with a filter arrangement having a carrier substrate ( 1 ), a resonator unit, and a reflection element ( 2 ) between the carrier substrate ( 1 ) and the resonator unit, characterized in that the reflection element ( 2 ) consists of a uinitary layer formed of an acoustically reflecting substance selected from the group consisting of silica aerogel or organic aerbgel, xerogel, glass foam, foam-type adhesive, foamed synthetic resin and a low density synthetic resin. 
     
     
       4. A receiver provided with a filter arrangement having a carrier substrate ( 1 ), a resonator unit, and a reflection element ( 2 ) between the carrier substrate ( 1 ) and the resonator unit, characterized in that the reflection element ( 2 ) consists of a unitary layer formed of an acoustically reflecting substance selected from the group consisting of silica aerogel or organic aerogel, xerogel, glass foam, foam-type adhesive, foamed synthetic resin and a low density synthetic resin. 
     
     
       5. A wireless data transmission system provided with a filter arrangement having a carrier substrate ( 1 ), a resonator unit, and a reflection element ( 2 ) between the carrier substrate ( 1 ) and the resonator unit, characterized in that the reflection element ( 2 ) consists of a unitary layer formed of an acoustically reflecting substance selected from the group consisting of silica aerogel or organic aerogel, xerogel, glass foam, foam-type adhesive, foamed synthetic resin and a low density synthetic resin. 
     
     
       6. An electronic component with a carrier substrate ( 1 ), a resonator unit, and a reflection element ( 2 ) between the carrier substrate ( 1 ) and the resonator unit, characterized in that the reflection element ( 2 ) consists of a unitary layer formed of an acoustically reflecting substance selected from the group consisting of silica aerogel or organic aerogel, xerogel, glass foam, foam-type adhesive, foamed synthetic resin and a low density synthetic resin. 
     
     
       7. A filter arrangement as claimed in  claim 1 , characterized in that a further reflection element ( 6 ) is arranged on the resonator unit. 
     
     
       8. A filter arrangement as claimed in  claim 1 , characterized in that a protective layer ( 7 ) of an organic and/or inorganic material is provided over the filter arrangement. 
     
     
       9. A filter arrangement as claimed in  claim 1 , characterized in that the carrier substrate ( 1 ) comprises a ceramic material, a ceramic material with a glass planarizing layer, a glass-ceramic material, a glass material, silicon, GaAs, or sapphire. 
     
     
       10. A filter arrangement as claimed in  claim 1 , characterized in that the resonator unit comprises a piezoelectric layer ( 4 ) of PbZr 0.15 Ti 0.85 O 3  doped with 2% lanthanum. 
     
     
       11. A filter arrangement as claimed in  claim 1 , characterized in that a layer of SiO 2  is present above and below a reflection element ( 2 ,  6 ). 
     
     
       12. A filter arrangement as claimed in  claim 1 , characterized in that an adhesive layer is arranged between the carrier substrate ( 1 ) and the reflection element ( 2 ).